Method of treating hydrocarbons



Jan. 2l,` 1941. w. A. CRAIG METHOD OF TEATING HYDROCARBONS Filed June28, 1958 Csar/V565 w /N 10s/TOR By m5@ ATTORNEYS' Patented Jan. 21, 1941UNITED STATES METHOD OF TREATING HYDROCARBONS Wallace Alexander Craig,Los Angeles, Calif., as-

signor to Richfield Oil Corporation, Los Angeles, Calif., a corporationof Delaware Application June 28, 1938, Serial No. 216,281

7 Claims.

This invention relates to the manufacture of a motor fuel and moreparticularly to a process of treating a mixture of a hydrocarbon oil andan aliphatic alcohol whereby the gum forming constituents and otherobjectionable bodies of the oil are removed and a product obtained whichdoes not require further treatment for sweeten- In carrying out theinvention, a mixture of a hydrocarbon oil and an aliphatic alcohol aretreated with a maintained solution of a heavy metal salt. I am aware ofa prior proposal for the removal of gum forming constituents and otherobjectionable bodies from hydrocarbons by treatment with heavy metalsal-ts. Such a process is disclosed in the patent to Arthur Lachman, No.1,790,622, granted January 27, 1931, and Reissue Patent No. 19,879,granted March 3, 1936.

In practicing the prior art process in which hydrocarbon oils aretreated with a maintained solution of a heavy metal salt, the gumforming constituents and certain other objectionable bodies in the oilare removed but the treated oil is sour and requires further treatment.Also the product obtains impurities which reduce the effect oftetraethyl lead when the latter is added to such fuel to increase itsoctane number.

In the present process wherein the hydrocarbon oil is first mixed withan aliphatic alcohol, the necessity of further treatment is avoided.When such mixture is subjected to 'a vapor phase treatment with amaintained solution of a heavy metal salt, the resultant product is no-tonly substantially free of gum forming constituents and coloredconstituents, but it is substantially sweet and therefore does notrequire further treatment.

While I am unable to state why the substances which account for most ofthe sourness in cracked gasoline, such as the mercaptans, are removedwhen a sour hydrocarbon oil is treated as herein described in thepresence of alcohol vapors, I have found that the water which isrecovered in the present process is alkaline, whereas in the prior artprocess of treating the hydrocarbon oil alone with a heavy metal salt,the recovered water contains small quantities of acid, such ashydrochloric acid, when the oil is treated with a Zinc chloridesolution. It is therefore probable that the alkaline condition of thesolution during treatment results in the conversion of the impuritiesinto products that are removed as nonvolatile solids.

As a further feature of the invention I have discovered that if abranched chain alcohol is used, the product obtained is not only free ofthe gum forming constituents and other objectionable constituents andsweet, but that an increased octane number is obtained. This increase inoctane number may possibly be due to the conversion of the branchedchain alcohols into branched chain ethers, which are soluble in thehydrocarbon oil, are insoluble in Water and possess excellent anti-knockproperties. erably employ a branched chain alcohol having more than twoatoms of carbon and less than seven atoms of carbon to the molecule.

'Ihe accompanying drawing is a diagrammatic view of one form ofapparatus suitable for use in practicing the process.

In the drawing, the reference numeral I designates a storage tank forthe mixture of hydrocarbon oil and alcohol to be treated. The tank isprovided with an outlet controlled by a valve 2 and connected to a pump3 capable of delivering predetermined amounts of liquid. The outlet ofthe pump is connected to a heater 4 which may be provided with anelectric heating coil 5 or other suitable heating means. The heater isin turn connected to a treating `tower 6 which may be provided withsuitable heating means, herein shown as a heating coil 1. Suitablepacking material 8 is arranged within the tower. A drain pipe 9 isconnected to the bottom of the tower and is controlled by a valve I 0. Apipe I I is connected to the tower adjacent the bottom and is controlledby a valve I2. This pipe may be employed for delivering steam to thetower. At the top of the tower a surge chamber I3 is formed. The top ofthe surge chamber is provided with a feed opening I4 controlled by avalve I5. The heavy metal salt or other treating reagent is charged intothe tower through this opening. A pipe I6 is connected to the top of thesurge chamber and forms a vapor line which extends into a coil arrangedWithin a condenser I'I. The lower end of the coil is connected to adischarge pipe 29. The condenser is provided with an inlet I8 and anoutlet I9 for water or other cooling fluid.

In practicing the process a suitable quantity of a mixture of an alcoholand a hydrocarbon oil is placed in tank I. The flow of the alcohol-oilmixture is controlled by the valve 2 and the pump 3. The mixture inliquid form is delivered to the heater 4 which is maintained at adesired temperature. It passes from the heater, largely as vapor, and isdelivered into the bottom of the treating tower 6. 'Ihe tower is chargedwith the desired treating reagent with the level of the liquid in thetreating tower almost up to the surge chamber I3. The temperature Withinthe I preftower is controlled by the heating coil 'l or other suitablemeans. If desired, steam may be introduced into the tower 'l throughpipe I2. The alcohol-oil vapors pass up through the tower and arebrought into intimate contact with the treating solution by the packingmaterial 8. At the beginning of an operation the vapors within the towerforce a portion of the treating solution into the surge chamber but thesurge chamber is of such size that no over-flow into the vapor lineoccurs. Equilibrium is eventually established and the solution tricklesdown into tower 8 as rapidly as it is lifted into the surge chamber. Thetreated vapors then pass through the delivery pipe l into the condenserl1 and the cooled material is conveyed to suitable storage pipes'through tank 20.

As a specic example of the operation of the process the treating tower 6was charged with a solution of zinc chloride in isopropyl alcohol. Amixture of two parts of raw cracked gasoline and one part of isopropylalcohol was placed in the storage tank I. This mixture was thendelivered to the heater 4 and the temperature of the gasoline-alcoholvapors, containing some liquid, entering the treating tower, wasmaintained at M-190 F. The temperature at the bottom of the tower was260-270 F., adjacent the center of the tower Z50-265 F., and at the topof the tower 210-2'78 F. The vapors passing through the system andrecovered by condensation consisted of water, an oil phase and gas. Thegas was assumed to be largely propylene. The water was a solution ofunreacted alcohol in water. The oil, after being washed with waterseveral times to remove any dissolved alcohol, was examined to determineits composition. A comparison of the raw cracked gasoline with therecovered treated material is shown below in the table. The tests towhich the oil was submitted are the tests prescribed for testingpetroleum products.

Table Raw cracked Raw gasoline Reercev cracked fraction cut t eqtedgasoline to E. P. of t k' treated stock 0c Gravity, API 50. 8 57. 0Color, Saybolt Red Yellow 20 Say. color after 4 hrs.

sunlight 16 Mercaptan content, gram mols/ 1000 liters 13. 4 16. G 0Copper dish gums, Ing/100 ml 279 191 12 Glass dish gums, mg./100 ml 86l0 ll Sulfur content, percent 0. 74 0. 66 0. 42 Octane number 70+ 72 75-A. S. T. M. distillation:

Initial boiling point, "F 118 120 99 5% 168 160 156 Percent recovered97.0 98.0 97. 5

The residual solution of zinc chloride removed from the treater at theend of the test was a water solution, the alcohol having been replacedby water. Equally good results would therefore have been obtained if anaqueous solution of Zinc chloride had been used.

The process as conducted and described was carried out with a Zincchloride solution. Other heavy metal salts can be used in place of Zincchloride. mean salts of Zinc, copper, cadmium, mercury, iron, chromium,manganese, aluminum, nickel or cobalt. These salts may be the chloride,bromide, sulfate, nitrate or any of the water or alcohol soluble saltsof the above named metals of organic acids, such as the sulfonic acid ofbenzene, toluene or xylene or the sulfo acids derived from the treatmentof petroleum oils with sulfuric acid.

While the method described herein is well adapted to carry out myinvention, I do not wish to be limited to the conditions herein setforth. Other means of contacting the alcohol-hydrocarbon oil vapor witha maintained solution of a heavy metal salt can be used, such, forexample, as a vessel provided with mechanical agitators. While I havedescribed in my example, a method of treating, in vapor phase, a rawcracked gasoline admixed with isopropyl alcohol and contacting thevapors with a maintained solution of zinc chloride, other aliphaticalcohols may be used; also solutions of other heavy metal salts may beemployed to effect the desired results. The choice of alcohol and thechoice of treating reagent depends upon the type of raw material to betreated and the characteristics that are desired in the nal product. Thepressure employed in the above example was atmospheric, but reducedpressure or super-atmospheric pressure can also be employed when neededto obtain the optimum operating conditions.

I claim:

l. The method of producing a motor fuel which comprises vaporizing amixture of a hydrocarbon oil and a branched chain aliphatic alcoholcontaining more than two and less than seven carbon atoms in a moleculeand contacting the vaporized mixture with a maintained solution of Zincchloride at a reacting temperature.

2. The method of producing a motor fuel which comprises contactingvapors of a hydrocarbon oil and an aliphatic alcohol containing morethan two and less than seven carbon atoms in the molecule with amaintained solution of zinc chloride at a reacting temperature andseparating the treated vapors from the solution.

3. In a process of purifying hydrocarbon oils the steps comprisingmixing substantially two parts of a hydrocarbon oil and substantiallyone part of a branched chain aliphatic alcohol containing more than twoand less than seven carbon atoms in a molecule and contacting thevaporized mixture with a maintained solution of zinc chloride at areacting temperature.

4. In a process of purifying hydrocarbon oils the steps comprisingmixing substantially two parts raw cracked gasoline and substantiallyone part isopropyl alcohol, vaporizing the mixture, and contacting thevaporized mixture with a maintained solution of zinc chloride at areacting temperature.

5. The method of producing a motor fuel which comprises vaporizing amixture of a hydrocarbon oil and a branched chain aliphatic alcoholcontaining more than two and less than seven carbon atoms in a molecule,and contacting the vaporized mixture with a maintained solution of achloride of a heavy metal of the group consisting of zinc, copper,cadmium, mercury, iron, chromium, manganese, aluminum, nickel and cobalt6. The method of producing a motor fuel which comprises vaporizing amixture of substantially two parts of a hydrocarbon oil andsubstantially By the term heavy metal salts Il two parts of raw crackedgasoline and substantially one part of an isopropyl alcohol andcontacting the vaporized mixture with a maintained `solution of achloride of a heavy metal of the group consisting of zinc, copper,cadmium, mercury, iron, chromium, manganese, aluminum, nickel andcobalt.

WALLACE ALEXANDER CRAIG.

